Patent GB-586106-A (GB)
Title: Improvements in or relating to mechanical follow-up and power amplifier systems
IPC: G05G19/00
Filed: 1938-09-14
Abstract: 5 8 6, , 1 0 6 . Mechanical follow - up systems. VICKERS-ARMSTRONGS, Ltd., and WATSON, J. P. Sept. 14, 1938, Nos. 26820/38 and 1495/39. [Class 118 (ii)] A mechanical follow-up system comprises a power amplifier with a sensitive input element responsive to movement in either direction of a primary control element through a cam disc and follower, displacement of which is restored by a mechanical connection to the output of the amplifier. Movement of the control shaft 37 rotates a cam disc 31 having two grooves 32, 33 of different radii connected by a portion 34 normally occupied by a pin 30 on lever 28. The resulting movement of lever 28 opens out a pair of spring-controlled scissor-levers 23 by movement of one of them, the other tending to move in the same direction and by engagement with pin 26 causing lever 22 on shaft 21 and therefore the sensitive input shaft 8 of the power amplifier to rotate and expand one or other of a pair of clutch bands, carried by arms. 12, 13 on sleeve 11, into engagement with one of a pair of oppositely rotating drums 6. The sleeve 11 drives the output shaft 16 which by means of differentials 20, 36 reacts on the shafts 35, 21 to restore the cam disc 31 and scissor-levers to relative normal positions. To minimise hunting, a factor dependent upon speed may be introduced into the mechanism for restoring the cam disc 31. This is effected by a speed measuring or integrating device 65 and differential gear 60. It may also be desirable to make this compensation according to a non-linear law on account of mechanical characteristics of the system, and for this purpose the speedmeasuring device may control a cam and lever device 71, 73 which influences the speed compensating mechanism by means of differential 67. The acceleration of the output movement may be limited by a fly-wheel carried by shaft 8 or 16. Modification, Figs. 6 and 7. In the cam device shown in Fig. 5 the amount of movement of the control shaft which can be recorded (the power driven drums need not be rotating when the shaft is moved) is somewhat less than 360 degrees in either direction. The arrangement shown in Fig. 6 imposes no limit. The initial operation of disc 31 and the scissor-levers 23 takes place as before, but on continued movement of shaft 37, lever 52 moves a sleeve carrying the disc 31 and a further disc 31A having complete circular grooves 45, 46 thereon, so that the pin 30 of lever 28 engages one or other of the grooves in disc 31A. The two grooves in the disc 31 extend only through an angle of just less than 180 degrees and have both ends connected by cam portions 43, 44. In this case if the control shaft 37 after having caused pin 30 to engage disc 31A, causes its re-engagement with disc 31, further rotation of 37 will bring the pin 30 into the other groove 41 or 42 as the case may be so that the drive of the output shaft will be reversed and the cam device will be restored to normal over the shortest path. The second Provisional Specification describes the power amplifier used in Specification 586,108.